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SubjectRe: [PATCH v6 6/8] coresight: add support for CPU debug module
On Thu, Apr 06, 2017 at 09:30:59PM +0800, Leo Yan wrote:
> Coresight includes debug module and usually the module connects with CPU
> debug logic. ARMv8 architecture reference manual (ARM DDI 0487A.k) has
> description for related info in "Part H: External Debug".
>
> Chapter H7 "The Sample-based Profiling Extension" introduces several
> sampling registers, e.g. we can check program counter value with
> combined CPU exception level, secure state, etc. So this is helpful for
> analysis CPU lockup scenarios, e.g. if one CPU has run into infinite
> loop with IRQ disabled. In this case the CPU cannot switch context and
> handle any interrupt (including IPIs), as the result it cannot handle
> SMP call for stack dump.
>
> This patch is to enable coresight debug module, so firstly this driver
> is to bind apb clock for debug module and this is to ensure the debug
> module can be accessed from program or external debugger. And the driver
> uses sample-based registers for debug purpose, e.g. when system triggers
> panic, the driver will dump program counter and combined context
> registers (EDCIDSR, EDVIDSR); by parsing context registers so can
> quickly get to know CPU secure state, exception level, etc.
>
> Some of the debug module registers are located in CPU power domain, so
> this requires the CPU power domain stays on when access related debug
> registers, but the power management for CPU power domain is quite
> dependent on SoC integration for power management. For the platforms
> which with sane power controller implementations, this driver follows
> the method to set EDPRCR to try to pull the CPU out of low power state
> and then set 'no power down request' bit so the CPU has no chance to
> lose power.
>
> If the SoC has not followed up this design well for power management
> controller, the user should use the command line parameter or sysfs
> to constrain all or partial idle states to ensure the CPU power
> domain is enabled and access coresight CPU debug component safely.
>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>

This is coming along well - a few comment below. In your next revision please
add GKH to the 'To' list.

Thanks,
Mathieu

> ---
> drivers/hwtracing/coresight/Kconfig | 14 +
> drivers/hwtracing/coresight/Makefile | 1 +
> drivers/hwtracing/coresight/coresight-cpu-debug.c | 667 ++++++++++++++++++++++
> 3 files changed, 682 insertions(+)
> create mode 100644 drivers/hwtracing/coresight/coresight-cpu-debug.c
>
> diff --git a/drivers/hwtracing/coresight/Kconfig b/drivers/hwtracing/coresight/Kconfig
> index 130cb21..8d55d6d 100644
> --- a/drivers/hwtracing/coresight/Kconfig
> +++ b/drivers/hwtracing/coresight/Kconfig
> @@ -89,4 +89,18 @@ config CORESIGHT_STM
> logging useful software events or data coming from various entities
> in the system, possibly running different OSs
>
> +config CORESIGHT_CPU_DEBUG
> + tristate "CoreSight CPU Debug driver"
> + depends on ARM || ARM64
> + depends on DEBUG_FS
> + help
> + This driver provides support for coresight debugging module. This
> + is primarily used to dump sample-based profiling registers when
> + system triggers panic, the driver will parse context registers so
> + can quickly get to know program counter (PC), secure state,
> + exception level, etc. Before use debugging functionality, platform
> + needs to ensure the clock domain and power domain are enabled
> + properly, please refer Documentation/trace/coresight-cpu-debug.txt
> + for detailed description and the example for usage.
> +
> endif
> diff --git a/drivers/hwtracing/coresight/Makefile b/drivers/hwtracing/coresight/Makefile
> index af480d9..433d590 100644
> --- a/drivers/hwtracing/coresight/Makefile
> +++ b/drivers/hwtracing/coresight/Makefile
> @@ -16,3 +16,4 @@ obj-$(CONFIG_CORESIGHT_SOURCE_ETM4X) += coresight-etm4x.o \
> coresight-etm4x-sysfs.o
> obj-$(CONFIG_CORESIGHT_QCOM_REPLICATOR) += coresight-replicator-qcom.o
> obj-$(CONFIG_CORESIGHT_STM) += coresight-stm.o
> +obj-$(CONFIG_CORESIGHT_CPU_DEBUG) += coresight-cpu-debug.o
> diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> new file mode 100644
> index 0000000..8470e31
> --- /dev/null
> +++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
> @@ -0,0 +1,667 @@
> +/*
> + * Copyright (c) 2017 Linaro Limited. All rights reserved.
> + *
> + * Author: Leo Yan <leo.yan@linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program. If not, see <http://www.gnu.org/licenses/>.
> + *
> + */
> +#include <linux/amba/bus.h>
> +#include <linux/coresight.h>
> +#include <linux/cpu.h>
> +#include <linux/debugfs.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/moduleparam.h>
> +#include <linux/pm_qos.h>
> +#include <linux/slab.h>
> +#include <linux/smp.h>
> +#include <linux/types.h>
> +#include <linux/uaccess.h>
> +
> +#include "coresight-priv.h"
> +
> +#define EDPCSR 0x0A0
> +#define EDCIDSR 0x0A4
> +#define EDVIDSR 0x0A8
> +#define EDPCSR_HI 0x0AC
> +#define EDOSLAR 0x300
> +#define EDPRCR 0x310
> +#define EDPRSR 0x314
> +#define EDDEVID1 0xFC4
> +#define EDDEVID 0xFC8
> +
> +#define EDPCSR_PROHIBITED 0xFFFFFFFF
> +
> +/* bits definition for EDPCSR */
> +#define EDPCSR_THUMB BIT(0)
> +#define EDPCSR_ARM_INST_MASK GENMASK(31, 2)
> +#define EDPCSR_THUMB_INST_MASK GENMASK(31, 1)
> +
> +/* bits definition for EDPRCR */
> +#define EDPRCR_COREPURQ BIT(3)
> +#define EDPRCR_CORENPDRQ BIT(0)
> +
> +/* bits definition for EDPRSR */
> +#define EDPRSR_DLK BIT(6)
> +#define EDPRSR_PU BIT(0)
> +
> +/* bits definition for EDVIDSR */
> +#define EDVIDSR_NS BIT(31)
> +#define EDVIDSR_E2 BIT(30)
> +#define EDVIDSR_E3 BIT(29)
> +#define EDVIDSR_HV BIT(28)
> +#define EDVIDSR_VMID GENMASK(7, 0)
> +
> +/*
> + * bits definition for EDDEVID1:PSCROffset
> + *
> + * NOTE: armv8 and armv7 have different definition for the register,
> + * so consolidate the bits definition as below:
> + *
> + * 0b0000 - Sample offset applies based on the instruction state, we
> + * rely on EDDEVID to check if EDPCSR is implemented or not
> + * 0b0001 - No offset applies.
> + * 0b0010 - No offset applies, but do not use in AArch32 mode
> + *
> + */
> +#define EDDEVID1_PCSR_OFFSET_MASK GENMASK(3, 0)
> +#define EDDEVID1_PCSR_OFFSET_INS_SET (0x0)
> +#define EDDEVID1_PCSR_NO_OFFSET_DIS_AARCH32 (0x2)
> +
> +/* bits definition for EDDEVID */
> +#define EDDEVID_PCSAMPLE_MODE GENMASK(3, 0)
> +#define EDDEVID_IMPL_EDPCSR (0x1)
> +#define EDDEVID_IMPL_EDPCSR_EDCIDSR (0x2)
> +#define EDDEVID_IMPL_FULL (0x3)
> +
> +#define DEBUG_WAIT_SLEEP 1000
> +#define DEBUG_WAIT_TIMEOUT 32000
> +
> +struct debug_drvdata {
> + void __iomem *base;
> e struct device *dev;
> + int cpu;
> +
> + bool edpcsr_present;
> + bool edcidsr_present;
> + bool edvidsr_present;
> + bool pc_has_offset;
> +
> + u32 edpcsr;
> + u32 edpcsr_hi;
> + u32 edprsr;
> + u32 edvidsr;
> + u32 edcidsr;
> +};
> +
> +static DEFINE_MUTEX(debug_lock);
> +static DEFINE_PER_CPU(struct debug_drvdata *, debug_drvdata);
> +static int debug_count;
> +static struct dentry *debug_debugfs_dir;
> +
> +static bool debug_enable;
> +module_param_named(enable, debug_enable, bool, 0600);
> +MODULE_PARM_DESC(enable, "Knob to enable debug functionality "
> + "(default is 0, which means is disabled by default)");

For this driver we have a debugFS interface so I question the validity of a
kernel module parameter. Other than adding complexity to the code it offers no
real added value. If a user is to insmod a module, it is just as easy to switch
on the functionality using debugFS in a second step.

> +
> +static void debug_os_unlock(struct debug_drvdata *drvdata)
> +{
> + /* Unlocks the debug registers */
> + writel_relaxed(0x0, drvdata->base + EDOSLAR);

Here the wmb is to make sure reordering (either at compile time or in the CPU)
doesn't happend. You need a comment here otherwise checkpatch will complain.
Speaking of which, did you run this through checkpatch?

> + wmb();
> +}
> +
> +/*
> + * According to ARM DDI 0487A.k, before access external debug
> + * registers should firstly check the access permission; if any
> + * below condition has been met then cannot access debug
> + * registers to avoid lockup issue:
> + *
> + * - CPU power domain is powered off;
> + * - The OS Double Lock is locked;
> + *
> + * By checking EDPRSR can get to know if meet these conditions.
> + */
> +static bool debug_access_permitted(struct debug_drvdata *drvdata)
> +{
> + /* CPU is powered off */
> + if (!(drvdata->edprsr & EDPRSR_PU))
> + return false;
> +
> + /* The OS Double Lock is locked */
> + if (drvdata->edprsr & EDPRSR_DLK)
> + return false;
> +
> + return true;
> +}
> +
> +static void debug_force_cpu_powered_up(struct debug_drvdata *drvdata)
> +{
> + bool retried = false;
> + u32 edprcr;
> +
> +try_again:
> +
> + /*
> + * Send request to power management controller and assert
> + * DBGPWRUPREQ signal; if power management controller has
> + * sane implementation, it should enable CPU power domain
> + * in case CPU is in low power state.
> + */
> + edprcr = readl_relaxed(drvdata->base + EDPRCR);
> + edprcr |= EDPRCR_COREPURQ;
> + writel_relaxed(edprcr, drvdata->base + EDPRCR);
> +
> + /* Wait for CPU to be powered up (timeout~=32ms) */
> + if (readx_poll_timeout_atomic(readl_relaxed, drvdata->base + EDPRSR,
> + drvdata->edprsr, (drvdata->edprsr & EDPRSR_PU),
> + DEBUG_WAIT_SLEEP, DEBUG_WAIT_TIMEOUT)) {
> + /*
> + * Unfortunately the CPU cannot be powered up, so return
> + * back and later has no permission to access other
> + * registers. For this case, should disable CPU low power
> + * states to ensure CPU power domain is enabled!
> + */
> + pr_err("%s: power up request for CPU%d failed\n",
> + __func__, drvdata->cpu);
> + return;
> + }
> +
> + /*
> + * At this point the CPU is powered up, so set the no powerdown
> + * request bit so we don't lose power and emulate power down.
> + */
> + edprcr = readl_relaxed(drvdata->base + EDPRCR);
> + edprcr |= EDPRCR_COREPURQ | EDPRCR_CORENPDRQ;
> + writel_relaxed(edprcr, drvdata->base + EDPRCR);
> +
> + drvdata->edprsr = readl_relaxed(drvdata->base + EDPRSR);
> +
> + /* Bail out if CPU is powered up */
> + if (likely(drvdata->edprsr & EDPRSR_PU))
> + return;

/* The core power domain got switched off on use, try again */
if (unlikely(!drvdata->edprsr & EDPRSR_PU))
goto try_again;

I understand you don't want to introduce a infinite loop but if that happens
here, something else has gone very wrong. The above readx_poll_timeout_atomic
loop should take care of bailing out in case of problems. That way you also get
to rid of the retried variable and the code is more simple.

> +
> + /*
> + * Handle race condition if CPU has been waken up but it sleeps
> + * again if EDPRCR_CORENPDRQ has been flipped, so try to run
> + * waken flow one more time.
> + */
> + if (!retried) {
> + retried = true;
> + goto try_again;
> + }
> +}
> +
> +static void debug_read_regs(struct debug_drvdata *drvdata)
> +{
> + u32 save_edprcr;
> +
> + CS_UNLOCK(drvdata->base);
> +
> + /* Unlock os lock */
> + debug_os_unlock(drvdata);
> +
> + /* Save EDPRCR register */
> + save_edprcr = readl_relaxed(drvdata->base + EDPRCR);
> +
> + /*
> + * Ensure CPU power domain is enabled to let registers
> + * are accessiable.
> + */
> + debug_force_cpu_powered_up(drvdata);
> +
> + if (!debug_access_permitted(drvdata))
> + goto out;
> +
> + drvdata->edpcsr = readl_relaxed(drvdata->base + EDPCSR);
> +
> + /*
> + * As described in ARM DDI 0487A.k, if the processing
> + * element (PE) is in debug state, or sample-based
> + * profiling is prohibited, EDPCSR reads as 0xFFFFFFFF;
> + * EDCIDSR, EDVIDSR and EDPCSR_HI registers also become
> + * UNKNOWN state. So directly bail out for this case.
> + */
> + if (drvdata->edpcsr == EDPCSR_PROHIBITED)
> + goto out;
> +
> + /*
> + * A read of the EDPCSR normally has the side-effect of
> + * indirectly writing to EDCIDSR, EDVIDSR and EDPCSR_HI;
> + * at this point it's safe to read value from them.
> + */
> + if (IS_ENABLED(CONFIG_64BIT))
> + drvdata->edpcsr_hi = readl_relaxed(drvdata->base + EDPCSR_HI);
> +
> + if (drvdata->edcidsr_present)
> + drvdata->edcidsr = readl_relaxed(drvdata->base + EDCIDSR);
> +
> + if (drvdata->edvidsr_present)
> + drvdata->edvidsr = readl_relaxed(drvdata->base + EDVIDSR);
> +
> +out:
> + /* Restore EDPRCR register */
> + writel_relaxed(save_edprcr, drvdata->base + EDPRCR);
> +
> + CS_LOCK(drvdata->base);
> +}
> +
> +static unsigned long debug_adjust_pc(struct debug_drvdata *drvdata)
> +{
> + unsigned long arm_inst_offset = 0, thumb_inst_offset = 0;
> + unsigned long pc;
> +
> + if (IS_ENABLED(CONFIG_64BIT))
> + return (unsigned long)drvdata->edpcsr_hi << 32 |
> + (unsigned long)drvdata->edpcsr;
> +
> + pc = (unsigned long)drvdata->edpcsr;
> +
> + if (drvdata->pc_has_offset) {
> + arm_inst_offset = 8;
> + thumb_inst_offset = 4;
> + }
> +
> + /* Handle thumb instruction */
> + if (pc & EDPCSR_THUMB) {
> + pc = (pc & EDPCSR_THUMB_INST_MASK) - thumb_inst_offset;
> + return pc;
> + }
> +
> + /*
> + * Handle arm instruction offset, if the arm instruction
> + * is not 4 byte alignment then it's possible the case
> + * for implementation defined; keep original value for this
> + * case and print info for notice.
> + */
> + if (pc & BIT(1))
> + pr_emerg("Instruction offset is implementation defined\n");
> + else
> + pc = (pc & EDPCSR_ARM_INST_MASK) - arm_inst_offset;
> +
> + return pc;
> +}
> +
> +static void debug_dump_regs(struct debug_drvdata *drvdata)
> +{
> + unsigned long pc;
> +
> + pr_emerg("\tEDPRSR: %08x (Power:%s DLK:%s)\n", drvdata->edprsr,
> + drvdata->edprsr & EDPRSR_PU ? "On" : "Off",
> + drvdata->edprsr & EDPRSR_DLK ? "Lock" : "Unlock");
> +
> + if (!debug_access_permitted(drvdata)) {
> + pr_emerg("No permission to access debug registers!\n");
> + return;
> + }
> +
> + if (drvdata->edpcsr == EDPCSR_PROHIBITED) {
> + pr_emerg("CPU is in Debug state or profiling is prohibited!\n");
> + return;
> + }
> +
> + pc = debug_adjust_pc(drvdata);
> + pr_emerg("\tEDPCSR: [<%p>] %pS\n", (void *)pc, (void *)pc);
> +
> + if (drvdata->edcidsr_present)
> + pr_emerg("\tEDCIDSR: %08x\n", drvdata->edcidsr);
> +
> + if (drvdata->edvidsr_present)
> + pr_emerg("\tEDVIDSR: %08x (State:%s Mode:%s Width:%dbits VMID:%x)\n",
> + drvdata->edvidsr,
> + drvdata->edvidsr & EDVIDSR_NS ? "Non-secure" : "Secure",
> + drvdata->edvidsr & EDVIDSR_E3 ? "EL3" :
> + (drvdata->edvidsr & EDVIDSR_E2 ? "EL2" : "EL1/0"),
> + drvdata->edvidsr & EDVIDSR_HV ? 64 : 32,
> + drvdata->edvidsr & (u32)EDVIDSR_VMID);
> +}
> +
> +static void debug_init_arch_data(void *info)
> +{
> + struct debug_drvdata *drvdata = info;
> + u32 mode, pcsr_offset;
> + u32 eddevid, eddevid1;
> +
> + CS_UNLOCK(drvdata->base);
> +
> + /* Read device info */
> + eddevid = readl_relaxed(drvdata->base + EDDEVID);
> + eddevid1 = readl_relaxed(drvdata->base + EDDEVID1);
> +
> + CS_LOCK(drvdata->base);
> +
> + /* Parse implementation feature */
> + mode = eddevid & EDDEVID_PCSAMPLE_MODE;
> + pcsr_offset = eddevid1 & EDDEVID1_PCSR_OFFSET_MASK;
> +
> + drvdata->edpcsr_present = false;
> + drvdata->edcidsr_present = false;
> + drvdata->edvidsr_present = false;
> + drvdata->pc_has_offset = false;
> +
> + switch (mode) {
> + case EDDEVID_IMPL_FULL:
> + drvdata->edvidsr_present = true;
> + /* Fall through */
> + case EDDEVID_IMPL_EDPCSR_EDCIDSR:
> + drvdata->edcidsr_present = true;
> + /* Fall through */
> + case EDDEVID_IMPL_EDPCSR:
> + /*
> + * In ARM DDI 0487A.k, the EDDEVID1.PCSROffset is used to
> + * define if has the offset for PC sampling value; if read
> + * back EDDEVID1.PCSROffset == 0x2, then this means the debug
> + * module does not sample the instruction set state when
> + * armv8 CPU in AArch32 state.
> + */
> + drvdata->edpcsr_present = (IS_ENABLED(CONFIG_64BIT) ||
> + (pcsr_offset != EDDEVID1_PCSR_NO_OFFSET_DIS_AARCH32));
> +
> + drvdata->pc_has_offset =
> + (pcsr_offset == EDDEVID1_PCSR_OFFSET_INS_SET);
> + break;
> + default:
> + break;
> + }
> +}
> +
> +/*
> + * Dump out information on panic.
> + */
> +static int debug_notifier_call(struct notifier_block *self,
> + unsigned long v, void *p)
> +{
> + int cpu;
> + struct debug_drvdata *drvdata;
> +
> + pr_emerg("ARM external debug module:\n");
> +
> + for_each_possible_cpu(cpu) {
> + drvdata = per_cpu(debug_drvdata, cpu);
> + if (!drvdata)
> + continue;
> +
> + pr_emerg("CPU[%d]:\n", drvdata->cpu);
> +
> + debug_read_regs(drvdata);
> + debug_dump_regs(drvdata);
> + }
> +
> + return 0;
> +}
> +
> +static struct notifier_block debug_notifier = {
> + .notifier_call = debug_notifier_call,
> +};
> +
> +static int debug_enable_func(void)
> +{
> + struct debug_drvdata *drvdata;
> + int cpu;
> +
> + for_each_possible_cpu(cpu) {
> + drvdata = per_cpu(debug_drvdata, cpu);
> + if (!drvdata)
> + continue;
> +
> + pm_runtime_get_sync(drvdata->dev);
> + }
> +
> + return atomic_notifier_chain_register(&panic_notifier_list,
> + &debug_notifier);
> +}
> +
> +static int debug_disable_func(void)
> +{
> + struct debug_drvdata *drvdata;
> + int cpu;
> +
> + for_each_possible_cpu(cpu) {
> + drvdata = per_cpu(debug_drvdata, cpu);
> + if (!drvdata)
> + continue;
> +
> + pm_runtime_put(drvdata->dev);
> + }
> +
> + return atomic_notifier_chain_unregister(&panic_notifier_list,
> + &debug_notifier);
> +}
> +
> +static ssize_t debug_func_knob_write(struct file *f,
> + const char __user *buf, size_t count, loff_t *ppos)
> +{
> + u8 val;
> + int ret;
> +
> + ret = kstrtou8_from_user(buf, count, 2, &val);
> + if (ret)
> + return ret;
> +
> + mutex_lock(&debug_lock);
> +
> + if (val == debug_enable)
> + goto out;
> +
> + if (val)
> + ret = debug_enable_func();
> + else
> + ret = debug_disable_func();

I don't think you need to install the handler every time the functionality is
switched on/off. I suggest to install the handler at boot time (or module
insertion time) and in the notifier handler, check the debug_enable flag before
moving on with the output.

> +
> + if (ret) {
> + pr_err("%s: unable to %s debug function: %d\n",
> + __func__, val ? "enable" : "disable", ret);
> + goto err;
> + }
> +
> + debug_enable = val;

Using a true/false value is probably better here. That way you don't end up
with miscellaneous values in debugFS.

> +out:
> + ret = count;
> +err:
> + mutex_unlock(&debug_lock);
> + return ret;
> +}
> +
> +static ssize_t debug_func_knob_read(struct file *f,
> + char __user *ubuf, size_t count, loff_t *ppos)
> +{
> + ssize_t ret;
> + char buf[2];
> +
> + mutex_lock(&debug_lock);
> +
> + buf[0] = '0' + debug_enable;
> + buf[1] = '\n';

snprintf()

> + ret = simple_read_from_buffer(ubuf, count, ppos, buf, sizeof(buf));
> +
> + mutex_unlock(&debug_lock);
> + return ret;
> +}
> +
> +static const struct file_operations debug_func_knob_fops = {
> + .open = simple_open,
> + .read = debug_func_knob_read,
> + .write = debug_func_knob_write,
> +};
> +
> +static int debug_func_init(void)
> +{
> + struct dentry *file;
> + int ret;
> +
> + /* Create debugfs node */
> + debug_debugfs_dir = debugfs_create_dir("coresight_cpu_debug", NULL);
> + if (!debug_debugfs_dir) {
> + pr_err("%s: unable to create debugfs directory\n", __func__);
> + return -ENOMEM;
> + }
> +
> + file = debugfs_create_file("enable", S_IRUGO | S_IWUSR,
> + debug_debugfs_dir, NULL, &debug_func_knob_fops);

Please align this properly.

> + if (!file) {
> + pr_err("%s: unable to create enable knob file\n", __func__);
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> + /* Use sysfs node to enable functionality */
> + if (!debug_enable)
> + return 0;
> +
> + /* Register function to be called for panic */
> + ret = atomic_notifier_chain_register(&panic_notifier_list,
> + &debug_notifier);
> + if (ret) {
> + pr_err("%s: unable to register notifier: %d\n",
> + __func__, ret);
> + goto err;
> + }
> +
> + return 0;
> +
> +err:
> + debugfs_remove_recursive(debug_debugfs_dir);
> + return ret;
> +}
> +
> +static void debug_func_exit(void)
> +{
> + debugfs_remove_recursive(debug_debugfs_dir);
> +
> + /* Unregister panic notifier callback */
> + if (debug_enable)
> + atomic_notifier_chain_unregister(&panic_notifier_list,
> + &debug_notifier);
> +}
> +
> +static int debug_probe(struct amba_device *adev, const struct amba_id *id)
> +{
> + void __iomem *base;
> + struct device *dev = &adev->dev;
> + struct debug_drvdata *drvdata;
> + struct resource *res = &adev->res;
> + struct device_node *np = adev->dev.of_node;
> + int ret;
> +
> + drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
> + if (!drvdata)
> + return -ENOMEM;
> +
> + drvdata->cpu = np ? of_coresight_get_cpu(np) : 0;
> + if (per_cpu(debug_drvdata, drvdata->cpu)) {
> + dev_err(dev, "CPU%d drvdata has been initialized\n",
> + drvdata->cpu);
> + return -EBUSY;
> + }
> +
> + drvdata->dev = &adev->dev;
> + amba_set_drvdata(adev, drvdata);
> +
> + /* Validity for the resource is already checked by the AMBA core */
> + base = devm_ioremap_resource(dev, res);
> + if (IS_ERR(base))
> + return PTR_ERR(base);
> +
> + drvdata->base = base;
> +
> + get_online_cpus();
> + per_cpu(debug_drvdata, drvdata->cpu) = drvdata;
> + ret = smp_call_function_single(drvdata->cpu,
> + debug_init_arch_data, drvdata, 1);
> + put_online_cpus();
> +
> + if (ret) {
> + dev_err(dev, "CPU%d debug arch init failed\n", drvdata->cpu);
> + goto err;
> + }
> +
> + if (!drvdata->edpcsr_present) {
> + dev_err(dev, "CPU%d sample-based profiling isn't implemented\n",
> + drvdata->cpu);
> + ret = -ENXIO;
> + goto err;
> + }
> +
> + if (!debug_count++) {
> + ret = debug_func_init();
> + if (ret)
> + goto err_func_init;
> + }
> +
> + if (!debug_enable)
> + pm_runtime_put(dev);
> +
> + dev_info(dev, "Coresight debug-CPU%d initialized\n", drvdata->cpu);
> + return 0;
> +
> +err_func_init:
> + debug_count--;
> +err:
> + per_cpu(debug_drvdata, drvdata->cpu) = NULL;
> + return ret;
> +}
> +
> +static int debug_remove(struct amba_device *adev)
> +{
> + struct device *dev = &adev->dev;
> + struct debug_drvdata *drvdata = amba_get_drvdata(adev);
> +
> + per_cpu(debug_drvdata, drvdata->cpu) = NULL;
> +
> + if (debug_enable)
> + pm_runtime_put(dev);
> +
> + if (!--debug_count)
> + debug_func_exit();
> +
> + return 0;
> +}
> +
> +static struct amba_id debug_ids[] = {
> + { /* Debug for Cortex-A53 */
> + .id = 0x000bbd03,
> + .mask = 0x000fffff,
> + },
> + { /* Debug for Cortex-A57 */
> + .id = 0x000bbd07,
> + .mask = 0x000fffff,
> + },
> + { /* Debug for Cortex-A72 */
> + .id = 0x000bbd08,
> + .mask = 0x000fffff,
> + },
> + { 0, 0 },
> +};
> +
> +static struct amba_driver debug_driver = {
> + .drv = {
> + .name = "coresight-cpu-debug",
> + .suppress_bind_attrs = true,
> + },
> + .probe = debug_probe,
> + .remove = debug_remove,
> + .id_table = debug_ids,
> +};
> +
> +module_amba_driver(debug_driver);
> +
> +MODULE_AUTHOR("Leo Yan <leo.yan@linaro.org>");
> +MODULE_DESCRIPTION("ARM Coresight CPU Debug Driver");
> +MODULE_LICENSE("GPL");
> --
> 2.7.4
>

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